Zahir Shah - a Pashtun - has been living in exile in Italy since he was deposed as king in 1973 after ruling Afghanistan for 40 years.

He has said that he is not coming with the intention of reclaiming the throne of Afghanistan, but he is expected to open the Loya Jirga or grand tribal council to be convened in June.

Special security arrangements have been made ahead of his return.

The Italians disclosed on Tuesday that carabinieri paramilitary police would take up positions inside the king's residence, working alongside Afghan bodyguards who would eventually take the job over.

Security has been reinforced at the villa where Zahir Shah will live, and nearby streets have been blocked off.

Loya Jirga

The Loya Jirga, to which elections have begun, will choose an 18-month transitional government to replace Mr Karzai's interim administration.

Some reports have also suggested that he would agree to lead Afghanistan again if the Loya Jirga asked him to do so.

Although the country appears to be moving towards an elected administration, there are increasing worries about a resurgence of al-Qaeda and Taleban activity, especially as the weather in the mountains improves.

Last week, there was an assassination attempt on the Afghan defence minister.